Method of making circuit panels



July 8, 1952 T. D. NiERENBERG METHOD OF MAKING CIRCUIT PANELS 2 SHEETS-SHEET 1 IIIIIIIA Filed March 30, 1950 waif TiqlE. INVENTOR.

ATTORNEY J y 1952 T. D. NIERENBERG METHOD OF MAKING CIRCUIT PANELS 2 SHEETS-SHEET 2 Filed March 30, 1950 A TTOE/VE Y Patented July 8, 1952 .2:

signor to Etched Products Corporation, Long Island City,-N-. Y; a. corporation'of New York Application March 30, 1950, sun No. 152,773 12 Claims. (01. 4143) conductors is imprinted on the foil surfaces by a suitable ink. While the ink is still'wet or tacky, the printed surfaces are coated with-an acid or etch resist "powder.

meson-printed p rtionsr- The article as then etched to empve' the fan from thejnon-printedsurface; portions; leaving have many otherapplications sucnasinlsinall radio receiver's and. the like. Asused auto-f busi'nes's 'fmachines, oneor both surfaces of, e ebtric panel has f rbili'tconductors thereonmaybe arranged to'c'ooper'ate 'With movable t closures or ,wip'er' arms of the machine v for to form complete circuit incooperation w thotherv electric conductors of the machine. Thecircuitclosures 'or wipers may, for example, be rotatable or oscillatable to connect with certain conductors on the. panel in predetermined so: 'qiuen'cesforinanysetpattern. i

"As presently Constructed, these circuit panels comprise asheet of dielectric material to which is. applied a preformed die cutsheeto'f copper or other conductive metal shaped to form the aesired' arrangement of circuit conductors, The surface .of the panel maybe suitably recessed,

by grinding, routing or thelike, to receive the diecut or otherwise formed copper sheet or copper tri .f m n e, c nd s The e u tant irwill 19.3. s not m what expe ve n s ruq e bu also. the c it. b a in sur ce-is nqhi sh #14 29 s ri u y tend somewhat abovethe surface of thedielectric panel even when the latter is recessed. Asa result, there is considerable resistance 11 he movement o fs-contactsover the panel in passing, for exam: ple, from a dielectric portion to a conductive portion. This causes Wear and tear on the contacts and on the circuit conductors, so that frequent replacement of the circuit closures and circuit pans sisn e a il-n accordance with thevpresent inventiongcircuit panels having printed circuits on one'or both surfaces are formed in a novelmanner whereby the conductive'and dielectric portions of, thesurface are flush and, levelthroughout; Thereby;

the aforementioned wear and tearionthe circuit closures: and conductors issubstantially '.e1imi-' nated, resulting in greatly increased lifetfor these elements. 'In addition; the invention method results in an inexpensively formedcircuit panel, having a. production cost which -"is' a fraction of that of the-prior'ar't panels.

In accordance with the invention; one or' both surfaces of= 'a dielectric panel; suchas one of'a pla'sticcomposition material, are-coated with' a fsl-ieet of-thin' metal muse-sh, as copperjfoil, 0.005? or" less-in thickness. Ihe foilis-appli'ed by pres sure or pressure combined with th ofa suitable adhesive. Following the foil appl1catioh,"the desired circuit design and "arrangement of circuit only thedesired "circuit design comprising con;

ductorsooated"with inhand th resistpowder;

Thefletched out portions'are then filled, to" a levelpreferably above-the surface-of the resist powder; by a suitable dielectric materials'uch as a -di elec-' tric ip'a'int. This paint' may be applied irra y desiredfashion; certain specific ways be n 'mentioned hereinafter, andis preferably a plies in successive layers. M r g "The printed surfaces of the panel are "then ground to" simultaneously remove some of the insulating material, the etch resistpowder, and the ink, all of theselmat'erials being removed to the samedepth. The resultant panel thus presents smooth, flush surfaces having the foil conductors separated by insulating materialin the etched out surface portions. The panel may thenbe baked to incre'ase the abrasion resistance of the insulator, after'which'the panel is cut to the desired ,peripheral contour "and formed with any desiredj'holes or apertures; With the" foregoing in mind, it is an object of the present'invention to provide an improved; inexpensive,circuitpanel. I

j Another object i's't'o provide 'such a panel having increased life, and characterized fbyfflush con mer'engagmg surfaces. w .These, and other objects, advantagesand novel featuresfof the invention will be apparent jfrom the ollowing" description and the accompanying drawings. Inthe drawings: j fFig' I is an elevation view offa'completed circui't panel processed in accordance with the fin v nu s: f. Y j "Fig. 2 and Fig; 3 are sectional and'elevation views, respectively, of the dielectric base' 'panel with the conductive foil applied thereto; I 4 .Fig. 4 is an elev'at'ion view ofthe panel after printing and the application of etch resist pow- .dertotheprintingy' Figs. 5 through 8 v ilinef5-'-5jof Fig. 4, illustrating the steps-of the invention method; 1 I i 'Fi'gs; Qfand 10 are elevation views of a-'-com'- pleted circuit "panel having circuits --pri nted-on both sides of the dielectric *base panel; and Figs. 11 through 16 are sectional views, onthe identical lines I l-ll of Figs. '9 and 10, illustrating successive steps in processing the panel of Figs f9 andlO. r 1 I Referring to Figs. 1 through '8,"th'e invention is iilu'strated as appliedto produce-aci-rcuit panel fare sectional views, 7 oni they I fsu'ccessive energizing circuits of the machine. v

It will be noted that the several conductors 25 have their inner ends 25a extending in radial 5 relation to a circular aperture 2| in the dielectric base panel 22 on whichthe conductors are mounted. correspondingly, the inner end26a of conductor 26 is arranged as a substantial semi circle concentric with aperture'2|. It will be noted that a circular marginal portion 23 of dielectric panel 22 lies between the inner ends of the conductors and aperture 2|.

Arotatable or oscillatable'circuit closure or contact member is arranged to engage inaperture, 2| and have. operative association with conductors 25 and 26, such member forming no partof the present invention and being a standard element of an automatic businessmachine. Itq-Will be understood, that circuit panel 20 is merely. exemplary of. a circuit panel produced according ftoi, the present invention, and the particular panel configuration, number of conductors, etc., is inln'o way a limitation of the invention principles. .l Figs. v2 .through '8 illustrates panel 20 according-tut the presentinvention. Referring to; Figs. land 2 in theufir'st step of the method as applied to circuit panel 20, a thin sheet of metal foil. 30, such as' copper'.foil,'for example, is applied to cover one surface of di-- electric base panel 22; Foil 30 which ,may, for example, be 0.005. thick'or' less, is applied to panel 22 under heavy pressurejor a combination of pressure and adhesive may be .used. As shown in Figsf l and 5', the. desired'circuit designis then imprinted "on foil 30, byasuitable adherent ink as at 3|. While, the ink is still wet or tacky, the foil covered surface is coated with 'an acid or etch resist powder' as at 32, the

steps" in forming powder adhering to'the inked portions forming whileth'e inkand resist powder coatings remain v on conductors 25 and 26, as may be seen from Material 33 may. be applied. in' any one of several ways. i'For example, adielectric material may, be silk-screened onto the etched out por tions of the'p'anel, or may be sprayed onto the panel Alternatively, nt jo the we may be thrown onto"the..,panel"and the excess wiped on". Thethickness.ofdielectric'material applied .to-the etched out surfaces is preferably greater than the combined'thickness of the foiL; ink and resistpowder remaining on the printed portions of the surface. This may be effectively accomplished byapplying the insulator. in successive layers. I v

The covered surface of the panel is then ground or. scraped to remove the resist powder-, ink. and insulator down to the level of the surfaceof 7 panel.

4 conductors 25 and 26. This is effected in a uniform manner so that the surface of the insulator 33 is flush with the surface of conductors 25 and '26 (see Fig. 8), thus providingiasmooth, level, flush surface on the circuit side of the Abrasion resistance of the insulator is increased by baking the completed panel, after which the panel is blanked to provide the desired peripheral contour and form aperture 2|.

The application of the invention to the formation of a circuit panel 40 having circuits printed on both surfaces is shown in Figs. 9 through 16.

Referring to Figs. 9 and 10-, which show opposite surfaces of the completed panel, a dielectric panel 42 is shown as having conductors 45, 46, 41 on one surface and conductors 48on the opposite surface. Panel 40' has apertures or recesses 39 and 4| in one surface, sfmilar to aperture 2| of panel 20, to receivesuitable jcircuit closures. Also, certain conductors 48 areshown' as terminating adjacent small holes 43' to receive wiresgeyelets or rivets to complete the circuit connections. H

Informing panel 40, sheets wand 50' of cop'-' per foil, for example, are applied to opposite surfaces of the dielectric'base panel'42 b pressure or by pressure and adhesive, as shownin Fig; 11.

The designs are then printed on both foil sheets,

asjindicated at 5|, 5|; and the sheets coated with resist powder adhering to the inked designs as at 52, 52 (Figs. '12 and 13)." The panelfis then etched to remove the non-printed and noncoated portions of foils 50, 50, leaving conductors 45, 46 and 4'! coated with the ink and the resist powder. The panel-now appears in' section as shown in Fig. 14.

The etched out portions of the panel then are filled with an insulating material 53, 53', as shown'in Fig. 15. The insulator-53, 53 may be applied as previously described, and may be simultaneously applied to both panel surfaces or to one surface at a time. The surfaces are then ground or scraped, either simultaneously or consecutively, to provide surfaces; flush withthe foil conductors as shown in Fig: "16. The formed panel is thenbacked to increase the abrasion resistance of the insulator-and blanked to shape and to form apertures or recesses .39, 4| and holes43. p

It should be noted that aperturesor recesses 39, 4| may be omitted and the corresponding spaces" merely act as end stops or bearings for the rotatable or oscillatable circuit closures or Wipers, i Although in the embodiments specifically outlined herein, the circuit design was imprinted with a tacky ink to which resist powder was applied, it is 'withinthe province of this invention to imprint the foil with a single medium, i. e. an ink or like material which is per se etch resistant, tode'fin'e the circuit-diagram.

. The invention providesa circuit panel-which hasone .or..more flush surfaces with conductors imprinted "thereon. .The flush relation of the conductive and dielectric surfaces decreases contact resistance and increases the panel life. Additionally, the panel is much less expensive than those produced by prior art methods.

While specificembodiments, of the invention have beenshown and described in detail to illustrate the application of the invention principles, itgshould be understoodthat the invention may be otherwise embodied without departing from u h ipq pl :What is -.claimed is: Y

1. .T e met odo r wing-a.e macm carrying panel which comprises applying conto form a predetermined 2. The method of forming an electric circuit I carrying panel which comprises applying con,- ductive foil to at least one surface of a panel of dielectric material, removing portions of said foil to form a predetermined circuit pattern including individual conductors, applying insulating material to the portions of such surface from which the foil has been removed, and finishing the surface of said insulating material flush with the surface of said foil.

3. The method of forming an electric circuit carrying panel which comprises applying conductive sheet material to at least one surface of a panel of dielectric material, removing portions of said sheet material to form a predetermined circuit pattern including individual conductors, applying insulating paint to the portions of such surface from which the sheet material has been removed, and finishing the surface of said paint flush with the surface of said sheet material.

4. The method of forming an electric circuit carrying panel which comprises applying conductive foil to at least one surface of a panel of dielectric material, removing portions of said foil to form a predetermined circuit pattern including individual conductors, applying insulating paint to the portions of such surface from which the foil has been removed, and finishing the surface of said paint flush with the surfaces of said foil.

5. The method of forming an electric circuit carrying panel which comprises applying a thin sheet of metal foil to each of the opposed surfaces of a panel of dielectric material, removing portions of said foil sheets to form predetermined circuit patterns, applying insulating paint to the portions of such surfaces from which the foil has been removed, and finishing the surface of said paint flush with the surface of said foil. v

6. The method of forming an electric circuit carrying panel which comprises applying conductive foil to at least one surface of a panel of dielectric material, applying an etch resistant layer to said foil in a predetermined circuit pattern, etching the panel to remove foil to form such predetermined circuit pattern, applying insulating material to the portions of such surface from which the foil has been removed to a level at least even with the surface of the resistant layer, and simultaneously removing the etch resistant layer and the insulating material to uncover the foil forming the circuit pattern and bring the surface of theinsulating material flush with the foil surface.

'7. The method of forming an electric circuit carrying panel which comprises applying conductive foil to at least one surface of a panel of dielectric material, imprinting with ink a predetermined circuit pattern on said foil, before the ink has dried, applying etch resist powder to the foil, whereby the powder will adhere to the printed pattern foil portions and will not adhere to the non-printed foil portions, etching the panel to remove the non-printed foil portions, applying insulating material to the portions of such surface from which the foil has been removed toa level at least even with the surface of the resist powder, and simultaneously removing the etch resist powder, the ink, and the insulating material to uncover the foil forming the circuit pattern and bring the surface of the insulating material flush with the foil surface.

8. The method of forming an electric circuit carrying panel which comprises applying a thin sheet of metal foil to each of the opposed surfaces of a panel of dielectric material, imprinting with ink predetermined circuit patterns on said foil sheets, .before the ink has dried, applying etch resist powder to the foil, whereby the powder will adhere to the printed pattern foil portions and will not adhere to the nonprinted foil portions, etching the panel to remove the nonprinted foil portions, applying insulating paint to the portions of such surfaces from which the sheet material has been removed to a level at least even with the surface of the resist powder, and with respect toeach surface, simultaneously removing the etch resist powder, the ink, and the paint to uncover the foil forming the circuit pattern and bring the surface of the paint flush with the foil surface.

9. The method of forming an electric circuit carrying panel which comprises applying a thin sheet of metal foil to each of the opposed surfaces of a panel of dielectric material, imprinting with ink predetermined circuit patterns on said foil sheets, before the ink has dried, applying etch resist powder to the foil, whereby the powder will adhere to the printed pattern foil portions and will not adhere to the non-printed foil portions. etching the panel to remove the non-printed foil portions, applying insulating paint to the portions of such surfaces fr-omwhich the sheet material has been removed to a level at least even with the surface of the resist powder, with respect to each surface, simultaneously removing the etch resist powder, the ink, and the paint to uncover the foil forming the circuit pattern and bring the surface of the paint fiush with the foil surface, and baking the panel to increase the abrasion resistance of the paint.

10. A method as claimed in claim 7, in which the insulating material is applied by silk screening.

11. A method as claimed in claim '7, in which the insulating material is sprayed on.

12. A methodas claimed in claim 7, in which the insulating material is applied in successive layers.

THEODORE D. NIERENBERG.

REFERENCES CITED The following references are of record in the file of this patent:

Lokker et al. May 9, 1950 

1. THE METHOD OF FORMING AN ELECTRIC CIRCUIT CARRYING PANEL WHICH COMPRISES APPLYING CONDUCTIVE SHEET MATERIAL TO AT LEAST ONE SURFACE OF A PANEL OF DIELECTRIC MATERIAL, REMOVING PORTIONS OF SAID SHEET MATERIAL TO FORM A PREDETERMINED CIRCUIT PATTERN INCLUDING INDIVIDUAL CONDUCTORS, APPLYING INSULATING MATERIAL TO THE PORTIONS OF SUCH SURFACE FROM WHICH THE SHEET MATERIAL HAS BEEN REMOVED, AND FINISHING THE SURFACE OF SAID INSULATING MATERIAL FLUSH WITH THE SURFACE OF SAID SHEET MATERIAL. 